Trench formation for dielectric filled cut region

ABSTRACT

A method for forming a gate cut region includes forming a tapered profile gate line trench through a hard mask, a dummy layer and a dummy dielectric formed on a substrate, forming a dummy gate dielectric and a dummy gate conductor in the trench and planarizing a top surface to reach the hard mask. The dummy gate conductor is patterned to form a cut trench in a cut region. The dummy gate conductor is recessed, and the cut trench is filled with a first dielectric material. The dummy layer is removed and spacers are formed. A gate line is opened up and the dummy gate conductor is removed from the gate line trench. A gate dielectric and conductor are deposited, and a gate cap layer provides a second dielectric that is coupled to the first dielectric material in the cut trench to form a cut last structure.

BACKGROUND

Technical Field

The present invention relates to semiconductor processing, and moreparticularly to processes and devices with improved cut regiondielectric fill to avoid shorting between structures.

Description of the Related Art

One commonly employed technique for forming gate structures involvesforming a line-type gate electrode structure above a layer of insulatingmaterial that is formed above an active region defined in asemiconductor substrate. Typically, the line-type gate electrodestructures are formed by defining long parallel line-type structures,i.e., gate electrode structures that extend across multiple spaced-apartactive regions and the isolation regions formed in the substrate betweensuch spaced-apart active regions. At some point later in the processflow, these long, line-type gate electrode structures are subsequently“cut” by performing an etching process to define the gate electrodeshaving the desired length.

After the gate electrodes are patterned, a sidewall spacer is typicallyformed around the perimeter of the substantially rectangular shaped gatestructure, i.e., the spacer is formed adjacent on all four sidesidewalls (two sidewalls and two end surfaces) of each of the patternedgate electrodes. In some cases, a thin liner layer may be formed on thegate structure prior to forming the sidewall spacer. The sidewallspacer, in combination with the gate cap layer, functions to protect thegate electrode structure in subsequent processing operations.

In the case where transistor devices are manufactured using so-calledgate-first processing techniques, the gate structures (gate electrodeplus the gate insulation layer) formed as described above are final gatestructures for the device. In the situation where transistor devices aremanufactured using so-called gate-last processing techniques, the gatestructures (gate electrode and gate insulation layer) formed asdescribed above are sacrificial in nature and will be subsequentlyremoved (after several process operations are performed) and replacedwith a final gate structure for the device. In the gate-last processingtechnique, the final gate structure typically includes one or morelayers of high-k insulating material and one or more layers of metalthat constitute at least part of the conductive gate electrode of thefinal gate structure.

Unfortunately, as device dimensions have decreased and packing densitieshave increased, it is more likely that, when epi semiconductor materialis formed in the source/drain regions, some of the epi material mayundesirably form on the end surfaces of the polysilicon/amorphoussilicon gate electrode. As packing densities have increased, theend-to-end spacing between two different gate electrode structuresformed above two different active regions has decreased, therebylimiting the physical size, i.e., the width, of the protective sidewallspacers. Additionally, as the pitch between adjacent gate structures hasdecreased, the width of the protective sidewall spacers must also bedecreased.

For example, in 7 nm technology processing, a few challenges or issuesinclude the following. In replacement metal gate recess processing, thegate length is too narrow, work function metal (WFM) tends to pinch-offduring deposition. It is very difficult to recess the WFM if there is avoid in the WFM. In forming the gate shape, a spacer image transfer(SIT) process may be employed. A lithography, etch, lithography, etch(LELE) is very difficult to use to pattern the gate shape (however, LELEmakes it is easy to define trench shapes). With SIT, it is notstraightforward to define certain device types (e.g., WIMPY devices),and separate mask sets are needed for other device types (e.g., for longchannel devices). Epi shorts at gate line-ends can occur since pass finsat the line end are so small. Epitaxial lateral growth can easily shortsource/drains (S/D) around the gate structure. Contact etch shorts atthe gate line-end are also issues since there is usually more damage togate line-ends than line-sides during spacer and contact etches. Inaddition, the 7 nm spacer target thickness is only 6 nm. While theshorts due to etching may be mitigated with a gate cut last process,this processing would require two flowable oxide fills, which creates athermal budget issue, especially for high percentage Ge, SiGe fins, andthis adds processing time and expense.

SUMMARY

A method for forming a gate cut region includes forming a taperedprofile gate line trench through a hard mask, a dummy layer and a dummydielectric formed on a substrate, forming a dummy gate dielectric and adummy gate conductor in the trench and planarizing a top surface toreach the hard mask. The dummy gate conductor is patterned to form a cuttrench in a cut region. The dummy gate conductor is recessed to expose ashallow trench isolation region in the substrate, and the cut trench isfilled with a first dielectric material. The dummy layer is removed andspacers are formed about a gate line. An interlevel dielectric (ILD)deposition fills gaps. The gate line is opened up to expose and removethe dummy gate conductor from the tapered profile gate line trench.

Another method for forming a gate cut region includes forming shallowtrench isolation (STI) regions in a substrate wherein one STI regioncorresponds to a central portion of a cut region; forming a hard mask, adummy layer and a dummy dielectric on the substrate; etching a taperedprofile gate line trench through the hard mask, the dummy layer and thedummy dielectric; forming a dummy gate dielectric and a dummy gateconductor in the trench; planarizing a top surface to reach the hardmask; patterning the dummy gate conductor to form a cut trench in thecut region; recessing the dummy gate conductor to expose the one STIregion in the substrate; filling the cut trench with a first dielectricmaterial; removing the dummy layer; forming spacers about a gate lineexposed by removing the dummy layer; epitaxially growing source anddrain regions adjacent to the spacers; filling gaps using an interleveldielectric (ILD) deposition; planarizing the ILD to open up the gateline to expose and remove the dummy gate conductor from the taperedprofile gate line trench; depositing a gate dielectric and gateconductor in the tapered profile gate line trench; and forming a gatecap layer to cap a gate structure and provide a second dielectric thatis coupled to the first dielectric material in the cut trench to form acut last structure.

A device having a gate cut region includes a tapered profile gate lineformed on a substrate. The tapered profile gate line includes a gatedielectric and a gate metal formed within the tapered profile andspacers formed on sidewalls of the tapered profile gate line. Source anddrain regions are formed adjacent to the spacers. A cut last structureis formed in a mid-portion along the tapered profile gate line in a cutregion. The cut region includes a first dielectric material formed on ashallow trench isolation region in the substrate and a second dielectricmaterial forming a gate cap layer and forming vertical interface regionsbetween the gate cap layer and the first dielectric material.

These and other features and advantages will become apparent from thefollowing detailed description of illustrative embodiments thereof,which is to be read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The disclosure will provide details in the following description ofpreferred embodiments with reference to the following figures wherein:

FIG. 1 is a cross-sectional view of a semiconductor device showing aschematic top view and two cross-sectional views depicting a formationof shallow trench isolation regions in a substrate in accordance withthe present principles;

FIG. 2 is a cross-sectional view of the semiconductor device of FIG. 1showing a schematic top view and two cross-sectional views depictingformation of a dummy dielectric, dummy layer and hard mask layer inaccordance with the present principles;

FIG. 3 is a cross-sectional view of the semiconductor device of FIG. 2showing a schematic top view and two cross-sectional views depicting atapered profile gate line etched into the dummy dielectric, dummy layerand hard mask layer in accordance with the present principles;

FIG. 4 is a cross-sectional view of the semiconductor device of FIG. 3showing a schematic top view and two cross-sectional views depicting adummy gate dielectric and a dummy gate conductor formed in the taperedprofile gate line in accordance with the present principles;

FIG. 5 is a cross-sectional view of the semiconductor device of FIG. 4showing a schematic top view and two cross-sectional views depicting apatterning process and subsequent partial dummy gate recess etching in acut region in accordance with the present principles;

FIG. 6 is a cross-sectional view of the semiconductor device of FIG. 5showing a schematic top view and two cross-sectional views depicting anextended recess of the dummy gate dielectric and dummy gate conductor toexpose a shallow trench isolation region in accordance with the presentprinciples;

FIG. 7 is a cross-sectional view of the semiconductor device of FIG. 6showing a schematic top view and two cross-sectional views depicting thetrench in the cut region filled with a dielectric material in accordancewith the present principles;

FIG. 8 is a cross-sectional view of the semiconductor device of FIG. 7showing a schematic top view and two cross-sectional views depicting thedummy layer removed in accordance with the present principles;

FIG. 9 is a cross-sectional view of the semiconductor device of FIG. 8showing a schematic top view and two cross-sectional views depictingspacers formed on the gate line and epitaxial contact growth inaccordance with the present principles;

FIG. 10 is a cross-sectional view of the semiconductor device of FIG. 9showing a schematic top view and two cross-sectional views depicting aninterlevel dielectric layer formed and planarized to expose the dummygate conductor in accordance with the present principles;

FIG. 11 is a cross-sectional view of the semiconductor device of FIG. 10showing a schematic top view and two cross-sectional views depicting thedummy gate conductor removed in accordance with the present principles;

FIG. 12 is a cross-sectional view of the semiconductor device of FIG. 11showing a schematic top view and two cross-sectional views depicting agate dielectric, gate conductor and gate cap formation in accordancewith the present principles;

FIG. 13 is a cross-sectional view of the semiconductor device of FIG. 12showing a schematic top view and two cross-sectional views depicting aninterlevel dielectric layer extended and patterned to form contact holesin accordance with the present principles;

FIG. 14 is a top schematic view showing a gate cut last region/structurein accordance with the present principles; and

FIG. 15 is a block/flow diagram showing a method for forming a gate cutregion in accordance with illustrative embodiments.

DETAILED DESCRIPTION

In accordance with the present principles, methods and devices areprovided that assist is improving the reliability of semiconductordevices and, in particular, improving the electrical isolation providedby gate cut regions. In accordance with particularly useful embodiments,line end epitaxial (epi) region shorts and line end epi nodules areavoided, resulting in a larger epitaxial growth process window forforming source and drain regions (S/D regions). Contact and silicideregion shorts are also reduced or avoided completely by the line end cutregion. This enables local interconnect structures. The gate cut regionhas no residual silicon material, generates no defects and provides agood gap fill after the cut. Interlevel dielectric (ILD) loss is alsominimized.

In conventional devices, it is not uncommon that some portion of thepolysilicon or amorphous silicon dummy gate electrode material will beexposed at the time epi semiconductor material is formed in thesource/drain regions of a planar or finFET device. As a result, episemiconductor material will undesirably form on the exposed portions ofa dummy gate electrode layer. The extent and amount of undesirable episemiconductor material formation will vary depending upon the particularapplication and the quality of the manufacturing processes used tomanufacture the device. In a worst case scenario, this undesirable episemiconductor material may form around the entire end surface of aparticular gate electrode so as to effectively form a conductive“bridge” between one or both of the source/drain regions and the gateelectrode.

In another example, such undesirable epi semiconductor material may spanthe space between the opposing end surfaces of two spaced-apart gateelectrode structures, wherein the epi material may form on one or bothof the spaced-apart gate structures. This epi “nodule” growth canprevent self-aligned contact trench etching down to the fins, whichcauses contact with no flow of electrical current. As a result of suchundesirable and unpredictable epi formation, the resulting semiconductordevices and the integrated circuits including such devices maycompletely fail or operate at less than acceptable performance levels.

The present principles address these shortcomings of conventionaldevices by providing a cut last region that is formed during a gateformation process flow. The present principles provide isolation fromepitaxial shorts for source and drain regions as well as shorts due tocontacts and silicide regions associated with the contacts. In oneembodiment, gate formation is improved by employing a tapered gateopening for the deposition of gate metal without pinch-off.

It is to be understood that the present invention will be described interms of a given illustrative architecture; however, otherarchitectures, structures, substrate materials and process features andsteps may be varied within the scope of the present invention.

It will also be understood that when an element such as a layer, regionor substrate is referred to as being “on” or “over” another element, itcan be directly on the other element or intervening elements may also bepresent. In contrast, when an element is referred to as being “directlyon” or “directly over” another element, there are no interveningelements present. It will also be understood that when an element isreferred to as being “connected” or “coupled” to another element, it canbe directly connected or coupled to the other element or interveningelements may be present. In contrast, when an element is referred to asbeing “directly connected” or “directly coupled” to another element,there are no intervening elements present.

The present embodiments may include a design for an integrated circuitchip, which may be created in a graphical computer programming language,and stored in a computer storage medium (such as a disk, tape, physicalhard drive, or virtual hard drive such as in a storage access network).If the designer does not fabricate chips or the photolithographic masksused to fabricate chips, the designer may transmit the resulting designby physical means (e.g., by providing a copy of the storage mediumstoring the design) or electronically (e.g., through the Internet) tosuch entities, directly or indirectly. The stored design is thenconverted into the appropriate format (e.g., GDSII) for the fabricationof photolithographic masks, which typically include multiple copies ofthe chip design in question that are to be formed on a wafer. Thephotolithographic masks are utilized to define areas of the wafer(and/or the layers thereon) to be etched or otherwise processed.

Methods as described herein may be used in the fabrication of integratedcircuit chips. The resulting integrated circuit chips can be distributedby the fabricator in raw wafer form (that is, as a single wafer that hasmultiple unpackaged chips), as a bare die, or in a packaged form. In thelatter case the chip is mounted in a single chip package (such as aplastic carrier, with leads that are affixed to a motherboard or otherhigher level carrier) or in a multichip package (such as a ceramiccarrier that has either or both surface interconnections or buriedinterconnections). In any case the chip is then integrated with otherchips, discrete circuit elements, and/or other signal processing devicesas part of either (a) an intermediate product, such as a motherboard, or(b) an end product. The end product can be any product that includesintegrated circuit chips, ranging from toys and other low-endapplications to advanced computer products having a display, a keyboardor other input device, and a central processor.

Reference in the specification to “one embodiment” or “an embodiment” ofthe present principles, as well as other variations thereof, means thata particular feature, structure, characteristic, and so forth describedin connection with the embodiment is included in at least one embodimentof the present principles. Thus, the appearances of the phrase “in oneembodiment” or “in an embodiment”, as well any other variations,appearing in various places throughout the specification are notnecessarily all referring to the same embodiment.

It is to be appreciated that the use of any of the following “/”,“and/or”, and “at least one of”, for example, in the cases of “A/B”, “Aand/or B” and “at least one of A and B”, is intended to encompass theselection of the first listed option (A) only, or the selection of thesecond listed option (B) only, or the selection of both options (A andB). As a further example, in the cases of “A, B, and/or C” and “at leastone of A, B, and C”, such phrasing is intended to encompass theselection of the first listed option (A) only, or the selection of thesecond listed option (B) only, or the selection of the third listedoption (C) only, or the selection of the first and the second listedoptions (A and B) only, or the selection of the first and third listedoptions (A and C) only, or the selection of the second and third listedoptions (B and C) only, or the selection of all three options (A and Band C). This may be extended, as readily apparent by one of ordinaryskill in this and related arts, for as many items listed.

Referring now to the drawings in which like numerals represent the sameor similar elements, FIGS. 1-13 each include an illustrative top view 10of device 8, which includes a section line XX′ along a polysiliconcontact replacement gate (PC) region 16, a section line YY′perpendicular through an epi/fin contact area in an active region (RX)12, and a section line ZZ′ perpendicular to the section line YY′ throughthe active gate which aligns along the fin direction in the activeregion 12. Cross-sectional views at each of XX′, YY′ and ZZ′ are shownin each of FIGS. 1-13. A cut region will be fabricated between activeregions (RX) 12 and 14 as well be described. It should be understoodthat process flow may be applied to gate first or dummy gate structures.The following description illustratively describes a process with dummygate structures.

Referring now to the drawings in which like numerals represent the sameor similar elements and initially to FIG. 1, a substrate 20 is shownhaving shallow trench isolation (STI) regions 22 formed therein. Thesubstrate 20 may include a bulk substrate, a semiconductor-on-insulator(SOI) substrate or any other suitable substrate. The substrate 20 mayinclude silicon, germanium, SiGe, or other suitable materials. It shouldbe understood that the present principles may be applied to planardevice fabricating, fin device fabrication or any other device typefabrication process.

Referring to FIG. 2, a dummy gate dielectric 26 is formed on thesubstrate 20 and over the STI regions 22. The dummy gate dielectric 26may include an oxide that is grown or deposited. A dummy layer 28 isformed over the dummy gate dielectric 26 by a deposition process, e.g.,a chemical vapor deposition (CVD) or the like. The dummy layer 28 mayinclude amorphous silicon or polysilicon. A hard mask 30 is formed onthe dummy layer 28. The hard mask 30 may include a nitride (e.g., SiN).

Referring to FIG. 3, a trench 32 is etched for placement of a gatestructure and the formation of a cut region. The trench 32 extends alongXX′ and has a profile as depicted in section ZZ′. The trench 32 includesa tapered profile (in section ZZ′). The tapered profile may be etched bya LELE process (lithography, etch, lithography, etch or doublelithography, double etch). The LELE process enables small dimensions(e.g., 5 nm-20 nm, or larger) and controlled profiles (e.g., uniformtapering).

Referring to FIG. 4, another dummy dielectric layer 34 (similar to layer26) is deposited over a top surface and in the trench 32. The trench 32is then filled with a dummy gate layer 36. The dummy gate layer 36 mayinclude amorphous silicon or polysilicon material 36. The top surfacecan be planarized using a chemical mechanical polish (CMP) process downto the hard mask 30.

Referring to FIG. 5, an organic planarizing (or patterning) layer (OPL)38 (or organic dielectric layer (ODL)) is deposited over a top surfaceof the device on the amorphous silicon material 36. The OPL 38 ispatterned using a cut mask (CT) to form an opening 40 in the OPL 38 in acut region (between regions 12 and 14). The OPL 38 may include aphoto-sensitive organic polymer comprising a light-sensitive materialthat, when exposed to electromagnetic (EM) radiation, is chemicallyaltered and thus configured by the cut mask (not shown) to be removedusing a developing solvent. For example, the photo-sensitive organicpolymer may be polyacrylate resin, epoxy resin, phenol resin, polyamideresin, polyimide resin, unsaturated polyester resin, polyphenylenetherresin, polyphenylenesulfide resin, poly(methyl methacrylate) orbenzocyclobutene (BCB). The OPL 38 provides an etch mask to etch intothe material 38 to partially recess the material and form a trench 42.

Referring to FIG. 6, the ODL 38 is stripped off of the surface of thematerial 36. Then, the material 36 is recessed by a dry etch or areactive ion etch to recess the material 36 to form a trench 44 down tothe isolation region 22 in section XX′. In section ZZ′ the material 36is also recessed to form recess 46. Trench 44 and recess 46 havesidewalls of material 28 protected from etching using the dielectriclayer 34.

Referring to FIG. 7, the trench 44 and recess 46 are filled with adielectric fill material 48. The dielectric fill material 48 may includesilicon nitride or other suitable dielectric material. The dielectricfill material 48 may then be planarized using, e.g., CMP. In this way, adielectric plug of material 48 lands on the isolation region 22 andextends upward through the cut region (between regions 12 and 14)separating the material 36. In section ZZ′, the material 48 acts as acap layer for a dummy gate structure 50. Here, the dummy gate structure50 follows the LELE tapered profile.

Referring to FIG. 8, the material 28 is removed by a selective etchprocess. The etch selectively removes, e.g., unprotected amorphoussilicon selective to, e.g., nitride (fill 48) and oxide (e.g.,dielectric 26, 34).

Referring to FIG. 9, spacers 52 are formed around gate line 16. Spacers52 may be formed by depositing a dielectric material, such as SiN andetching by, e.g., RIE to remove the spacer layer from horizontalsurfaces. The RIE removes dummy dielectric 26 to expose the substrate 20(in sections YY′ and ZZ′). An epitaxial growth process, e.g., molecularbeam epitaxy, or the like) is performed to grow source and drain (S/D)regions 54 (or S/D contacts). The S/D regions 54 may be doped in-situ orafter formation. The portion of layer 48 in trench 44 blocks epitaxialshorts between source and drain regions 54 across the cut region (e.g.,between region 12 and region 14).

Referring to FIG. 10, a gap fill process is performed. A gap filldielectric 56 is deposited over the device 8. The gap fill dielectric 56may include a flowable material, such as a flowable oxide. The gap filldielectric 56 forms a portion of the Interlevel Dielectric (ILD). Thegap fill dielectric 56 is then planarized, e.g., by CMP, to expose thematerial 36 (in line 16 and structure 50).

Referring to FIG. 11, the material 36 (dummy gate) is removed byselective etching to expose the dummy gate dielectric layer 26 (insections XX′ and ZZ′) in trenches 58. The dummy gate dielectric layer 26is then removed.

Referring to FIG. 12, gate structures are formed by etching the dummygate dielectric 26 and depositing a gate dielectric 60. The gatedielectric 60 may include a high-k dielectric material (e.g. HfO₂). Agate metal 62 is deposited (the gate dielectric 60 is formed below thegate metal 62). The gate metal 62 may include a work function metaland/or other metal layers. In accordance with one aspect of the presentprinciples, the tapered profile provided for the gate opening permitsthe formation of thin metal layers without the issue of pinch-off. Inone embodiment, the metal layers 62 may include a work function metal(e.g., Ti, Pt) and a bulk metal (e.g., W). The metal layers 62 for thegate metal may be formed by conformal deposition processes followed by aCMP process. Then, a gate cap layer 64 may be deposited and planarized.The gate cap layer 64 may include silicon nitride or other dielectricmaterial. Other gate formation processes may also be performed.

Referring to FIG. 13, the ILD layer (56) is extended by an additionaldeposition process to form layer 66. Layer 66 (ILD) may include oxidealthough other dielectric materials may be employed. The ILD 66 isopened up to form trenches 68 for the formation of contacts. The ILD 66is patterned to expose S/D regions 54 for landing a self-aligned contact(SAC) after trench etching and stripping any protective layer on theepitaxial surface. Prior to forming the contact conductor (not shown) asiliciding process may be performed to form a silicide on a contactlanding position. The contact and silicide, when formed in the trenches68, are electrically isolated from the gate metal 62 by layer 48 and caplayer 64. The cap layer 64 extends over a top and sides of the gatemetal 62, and the layer 48 separates the gate metals between regions 12and 14. Region 44 also isolates S/D regions between regions 12 and 14. Acut last structure 72 includes vertical interface regions 74 between thecap layer 64 and the region 44 to provide substantial protection fromshorts in epitaxially grown material, and for shorts between contactand/or silicide materials.

Referring to FIG. 14, a top schematic view shows a gate cut lastregion/structure 72. Gate regions 82 are disposed between S/D regions.The S/D regions in this embodiment include epitaxial growth regions 54and fins 84. The gate line 16 runs through adjacent active regions 12and 14. A spacer 80 is formed around the gate line 16.

In accordance with the present principles, the gate structure 16 isformed in a tapered profile that permits the formation of thin materialswithout pinch-off. This profile enables the use of smaller gatestructures, e.g., sub-17 nm structures, and preferably 7 nm or less. Inaddition, the patterning process for the gate structure is also easierto perform since e.g., a LELE process may be employed to form a trench.S/D to S/D region shorts (in adjacent areas), and gate line to contactand/or silicide region shorts are significantly reduced or eliminated.Further, in accordance with the present embodiments, there is no needfor multiple flowable oxide deposition steps to form the cut laststructure.

Referring to FIG. 15, a method for forming a gate cut region is shown inaccordance with illustrative embodiments. In some alternativeimplementations, the functions noted in the blocks may occur out of theorder noted in the figures. For example, two blocks shown in successionmay, in fact, be executed substantially concurrently, or the blocks maysometimes be executed in the reverse order, depending upon thefunctionality involved. It will also be noted that each block of theblock diagrams and/or flowchart illustration, and combinations of blocksin the block diagrams and/or flowchart illustration, can be implementedby special purpose hardware-based systems that perform the specifiedfunctions or acts or carry out combinations of special purpose hardwareand computer instructions.

In block 102, shallow trench isolation (STI) regions are formed in asubstrate wherein one STI region corresponds to a central portion of acut region. The substrate may include a bulk substrate or asemiconductor-on-insulator substrate. In block 104, a hard mask, a dummylayer and a dummy dielectric are formed on the substrate. In block 106,a tapered profile gate line trench is etched through the hard mask, thedummy layer and the dummy dielectric. The tapered profile gets largerthe further the distance from the substrate. The tapered profile helpsto eliminate pinch-off of metal layers (e.g., WFM, etc.) when depositingthe metal layers in the gate trench. The tapered profile gate linetrench may be etched using a lithography, etch, lithography, etch (LELE)process, which can form a near perfect taper.

In block 108, a dummy gate dielectric and a dummy gate conductor areformed in the trench. In block 110, a top surface is planarized to reach(expose) the hard mask. In block 112, the dummy gate conductor ispatterned and partially recessed to form a cut trench in the cut region.In block 114, the patterning layer is removed, and the dummy gateconductor and dummy gate dielectric are recessed to expose the STIregion in the substrate. Recessing the dummy gate conductor includesforming a deeper recess at a central portion of the cut region than sideregions and recessing the central portion to first expose the one STIregion.

In block 116, the cut trench is filled with a first dielectric material.The first dielectric material may include SiN, although other dielectricmaterials may be employed. In block 118, the dummy layer is removed. Thedummy gate dielectric can provide an etch stop layer for removing thedummy layer. In block 120, spacers are formed about a gate line exposedby removing the dummy layer.

In block 122, source and drain regions may be epitaxially grown adjacentto the spacers. In block 124, gaps are filled using an interleveldielectric (ILD) deposition. In block 126, the ILD is planarized to openup the gate line to expose and remove the dummy gate conductor from thetapered profile gate line trench. In block 130, a gate dielectric andgate conductor are deposited in the tapered profile gate line trench. Inblock 132, a gate cap layer is formed to cap a gate structure andprovides a second dielectric that is coupled to the first dielectricmaterial in the cut trench to form a cut last structure. In block 134,the ILD is extended over the gate line and etched to form contact holesin the ILD, stopping on the second dielectric material in the cut regionfor a self-aligned contact etch. The second dielectric material mayinclude SiN, although other dielectric materials may be employed.

Having described preferred embodiments for trench formation fordielectric filled cut region (which are intended to be illustrative andnot limiting), it is noted that modifications and variations can be madeby persons skilled in the art in light of the above teachings. It istherefore to be understood that changes may be made in the particularembodiments disclosed which are within the scope of the invention asoutlined by the appended claims. Having thus described aspects of theinvention, with the details and particularity required by the patentlaws, what is claimed and desired protected by Letters Patent is setforth in the appended claims.

The invention claimed is:
 1. A device having a gate cut region,comprising: a tapered profile gate line formed on a substrate, thetapered profile gate line including a gate dielectric and a gate metalformed within the tapered profile and spacers formed on sidewalls of thetapered profile gate line; source and drain regions formed adjacent tothe spacers; and a cut last structure formed in a mid-portion along thetapered profile gate line in a cut region, the cut region including afirst dielectric material formed on a shallow trench isolation region inthe substrate and a second dielectric material forming a gate cap layerand forming vertical interface regions between the gate cap layer andthe first dielectric material.
 2. The device as recited in claim 1,wherein the tapered profile gate line includes a gradual tapered profileformed by using a lithography, etch, lithography, etch (LELE) process.3. The device as recited in claim 1, wherein the first dielectric andthe second dielectric include silicon nitride.
 4. The device as recitedin claim 1, further comprising an interlevel dielectric layer (ILD)formed over the cap layer, and opened up to form contacts therein. 5.The device as recited in claim 4, wherein the contacts are formed overthe vertical interface regions between the gate cap layer and the firstdielectric material.
 6. The device as recited in claim 1, wherein thetapered profile gate line prevents pinch-off for metal layers depositedtherein.
 7. The device as recited in claim 1, wherein the taperedprofile includes a larger taper dimension as distance increases from thesubstrate.